Lifetime comorbid substance misuse in patients newly diagnosed with bipolar disorder

Comorbid substance use is common in patients with bipolar disorder (BD) and associated with a more severe illness course and higher mortality rates. We aimed to investigate 1) the prevalence of lifetime comorbid substance misuse in patients with newly diagnosed BD compared with healthy controls (HC), and 2) differences in illness characteristics between patients with and without comorbid substance misuse.

We included 376 patients with newly diagnosed BD and 200 HC. Lifetime substance misuse (including alcohol and drug use) was identified through baseline interview and through systematic review of electronic health records.

The prevalence of lifetime substance misuse was higher for patients with newly diagnosed BD (43%). Patients with BD had a high prevalence of lifetime comorbid drug misuse (38%) than alcohol misuse (19%). Among patients, lifetime substance misuse was associated with male sex (OR = 2.86 [1.82; 4.55] p < 0.001), childhood trauma (β = 5.33 [2.68; 7.99], p = 0.003), BD type I (OR = 1.71 [1.09; 2.68], p = 0.042), presence of suicide attempts (OR = 2.26 [1.36; 3.75], p = 0.005) and more sick days the preceding year (β = 41.43 [16.90; 65.96], p = 0.012).

Information regarding substance use was partly gathered retrospectively using electronic health records. HC were recruited among blood donors and may not be representative of the general population.

We found a high prevalence of lifetime comorbid substance misuse, particularly drug misuse in patients with newly diagnosed BD. Lower clinical focus on drug use than alcohol may have contributed to higher observed prevalence of drug use. This highlights the need for early clinical assessment and integrated treatment.